Penicillinase was immobilized by glutaraldehyde-bovine serum albumin and sodium alginate was used for the construction of enzyme biosensors in determination of trace penicillin in milk. Penicillinase activity was determined by potentionmetric method. At low concentrations, the response time of the electrode modified by the method of crossing-link was 30～60 s, and the electrode showed high sensitivity. Linear detection range from 1.40×10 -3 to 3.36×10 -2 mmol/L in PBS and from 5.61×10 -2 to 3.36× 10 -1 mmol/L in milk were achieved. The electrode can be used for at least 7 d with perfect reproducibility during the first 4 d. The life of the electrode was 30 d.
This paper reports a novel rare interesting crystal structures of gadolinium 2-fluorobenzoato (2-FBA) complex containing 1,10-phenanthroline (phen). The two non-equivalent binuclear molecules, [Gd(2-FBA)3(phen) (CH3CH2OH)]2 and [Gd(2-FBA)3(phen)]2, exist in the asymmetric unit of the crystal. The molecular structure of [Gd (2-FBA)3(phen)(CH3CH2OH)]2 shows that the Gd3+ ion is eight-coordinated by five O atoms from five 2-FBA groups and one O atom from one ethanol molecule and two N atoms from phen molecule. 2-FBA groups adopt monoden- tate and bridging two coordination modes. The molecular structure of [Gd(2-FBA)3(phen)]2 shows that the Gd3+ ion is coordinated by nine atoms, seven O atoms from five 2-FBA groups and two N atoms from phen molecule. The 2-FBA groups link Gd3+ ion in chelating, bridgingand chelating-bridgingthree coordination modes. CCDC: 273106.
